This invention generally relates to open-end wrenches, and specifically relates to such a wrench having formations in the jaw surfaces which enable engagement of a portion of each of two fastener sides without engaging any of the corners of the fastener.
The usual open-end wrench consists of an elongated handle and a wrenching head on either or both ends. The head includes two jaws respectively with planar jaw surfaces that engage opposite sides of a polygonal fastener.
To tighten or loosen a fastener, torque is applied, the resultant forces tending to spread the jaws and in certain instances cause them to break. The stress at any location on each jaw is directly proportional to the distance to the point at which the force is applied, such point being where the most significant contact between the jaw and the fastener side occurs. In the usual wrench, the force is essentially perpendicular to the jaw surfaces and is, therefore, maximized so as to increase the likelihood of spread of the jaws or breakage.